Polyimides or polyamides have been used for a liquid crystal alignment film capable of orienting liquid crystal molecules in one direction. A polyimide film is generally prepared by coating a polyamic acid solution on a substrate followed by ring-closure of the acid while heating to obtain the desired polyimide film thereon. However, in this case, there is a problem in that the film is often colored by heating whereby the colored film often adversely affects the appearance of the device prepared therefrom and also deteriorates the light-resistance of the film itself. In addition, heating at a temperature of at least 250.degree. C. is necessary for conducting the ring closing reaction, and the heating at such a high temperature has a risk of causing deterioration of plastic substrates and color filters. Moreover, since polyimides generally have poor adhesion to a glass substrates, it is necessary to improve the adhesiveness thereof by using a silane coupling agent or a silane-containing diamine compound as described in JP-A-58-72924 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"). However, the use of the silane coupling agent causes a problem in the stability of the solution, and the use of silane-containing diamine compound necessarily involves a problem of high cost since the monomer must be synthesized separately. Polyamides also show poor adhesion to the substrates and have the same problems as the polyimides.
Recently, an attempt has been made using a liquid crystal polymer as an alignment film as disclosed in, for example, JP-A-2-190144. When the liquid crystal polymer is used, the coated film need not be heated for effecting the ring-closing reaction and also deterioration of the substrate can be avoided without causing coloring of the coated film and adversely affecting the light-resistance. Further, the liquid crystal polymer shows good adhesiveness to the glass substrate, and thus additives such as silane coupling agent are not required. However, since conventional liquid crystal polymers have problems in that they have poor solubility and are therefore not easily coated on a substrate. Thus, practical uses of liquid crystal polymers are limited to particular polymers. In order to solve such problems, a liquid crystal polymer having a high solubility in the solvent which is generally used for spin-coating has been developed as disclosed in Japanese Patent Application No. Hei-3-324334. This liquid crystal polymer is very effective because of its excellent solubility and high capability of orienting the liquid crystal, but it precipitates a polymer under a high humidity condition and therefore must be stored under low humidity conditions such as in a nitrogen atmosphere. Accordingly, such liquid crystal polymers still require an improvement from a practical standpoint.